1 The Nature of Life on Earth (Chap. 5 - Bennett & Shostak) Notes for Chapter 5 HNRS 228 Prof. Geller

2 Overview of Chapter 5 zDefining Life (5.1) yIts properties, evolution and definition zCells: The basic units of life (5.2) yStructure, composition, prokaryotes, eukaryotes zMetabolism: The chemistry of life (5.3) yEnergy needs and sources; water zDNA and Heredity (5.4) yStructure, replication, genetic code

3 Overview of Chapter 5 zLife at the Extremes (5.5) yExtremophiles and their implications zEvolution as Science (5.6)

4 Properties of Living Systems zNot laws zFrom Bennett & Shostak: yOrder (hierarchy) yReproduction yGrowth and development yEnergy use yResponse to the environment (open systems) yEvolution and adaptation

5 Properties of Living Systems zFrom Other Sources yHierarchical organization and emergent properties yRegulatory capacity leading to homeostasis yDiversity and similarity yMedium for life: water (H 2 O) as a solvent yInformation Processing

6 Properties of Living Systems: Order zDefine “random” zDefine “order” in an abiotic system zWhy is “order” an important property” zExamples of “order” in living systems yLevel of a biomolecule yLevel of the cell yLevel of the organelle yLevel of an ecosystem zRelate to hierarchical

7 Properties of Living Systems: Reproduction zDefine “reproduction” in abiotic terms yE.g., fire, crystals zDefine “reproduction” in biotic terms yWhy is it important property of living systems? zExamples in living systems yMicrobes (fission) yCells (mitosis) yWhole organisms xDonkey

8 Properties of Living Systems: Growth and Development zDefine “growth” zDefine “development” zWhy are “growth and development” important properties of living systems zExamples in living systems yOrganisms grow yOrganisms develop zExamples in abiotic systems yIce crystals yFire

9 Properties of Living Systems: Energy Use zDefinitions yEnergy capture xAutotrophs (photoautotrophs, chemoautotrophs) xHeterotrophs (saprovores, carnivores, omnivores, etc.) yEnergy utilization (1 st and 2 nd Laws of Thermodynamics) yEnergy storage xChemical bonds (covalent C-C bonds) and exothermic reactions xATP (adenosine triphosphate) and ADP (adenosine diphosphate) yEnergy dissipation (2 nd Law of Thermodynamics) zWhy is “energy use” and important property of living systems?

10 Properties of Living Systems: Energy Use Catabolism Biosynthesis ATP ADP

11 Metabolic “Class”

12 Properties of Living Systems: Response to the Environment zDefine an “open” versus “closed” system yInteraction with the environment yStimulus followed by a response zWhy is “response to the environment” an important property? zExamples in living systems yLeaf orientation to the sun yEyes yEars

13 Properties of Living Systems: Evolution and Adaptation zDefine “evolution” zDefine “adaptation” zWhy is “evolution and adaptation” an important property in living systems? zExamples of evolution in living systems yMacroscale: origin of species and taxa yMicroscale: xmicrobes resistant to antibiotics xmoths resistant to air pollution zExamples of adaptation yArticulation of the joints in animals yPlanar structure of leaves

14 Properties of Living Systems: Hierarchical Organization zDefine “hierarchical organization” ydiagram of atoms to biomolecules to organelles to cells to tissues, etc. zDefine “emergent properties” yEmergence of “novel and unanticipated” properties with each step of hierarchy zExamples in living systems yHierarchy yEmergent properties

15 Properties of Living Systems: Regulatory Capacity zDefine “regulatory capacity” yRelate to open systems zDefine “homeostasis” yRole of feedbacks (positive and negative) and cybernetics zWhy is “regulatory capacity and homeostasis” and important property of living systems? zExamples yMolecular biology: gene regulation yBiochemistry: enzymes yOrganisms: temperature yGlobe: “Parable of the Daisyworld”

16 Properties of Living Systems: Regulatory Capacity State Variable State Variable Sensor Set Point Positive Feedback Negative Feedback

17 Properties of Living Systems: Diversity and Similarity zDefine “diversity” yHallmark of all life (1.5 M known species; 100 M expected) zDefine “similarity” yHallmark of all life zWhy are “diversity and similarity” important properties of living systems? z Examples of similarity xBiochemistry xStructure and Morphology xDNA and RNA

18 Properties of Living Systems: Medium for Metabolism zDefine a “medium for metabolism” and why an important property of living systems? zRole of “water” as medium yPhysical properties xAbundance in universe, state as a f unction of temperature, freezing properties yChemical properties xBonding, polarity, diffusion, osmosis

19 Properties of Living Systems: Information zDefine “information” and relate to order zWhy is “information” an important property of living systems” zNecessary states of “information” yStorage yTranslation yTemplate/Copying yCorrecting (spell check) zExamples yDNA yRNA

20 Properties of Living Systems: Recap zDiversity and similarity of structure and function zWhat does above suggest? yRecurrent theme of similar properties xHigh fitness value xCommon ancestor yRecurrent theme of diverse properties xHigh fitness value xDiversity of habitats xCreativity and spontaneity of evolution zWhat mechanism can account for both similarity and diversity?

21 iClicker Question zWhich of the following is not a key property of life? yAThe maintenance of order in living cells. yBThe ability to evolve over time. yCThe ability to violate the second law of thermodynamics.

22 iClicker Question zNatural selection is the name given to yAthe occasional mutations that occur in DNA. yBthe mechanism by which advantageous traits are preferentially passed on from parents to offspring. yCthe idea that organism can develop new characteristics during their lives and then pass these to their offspring.

23 iClicker Question zWhich of the following is not a source of energy for at least some forms of life on Earth? yAInorganic chemical reactions. yBEnergy release from plutonium. yCConsumption of pre-existing organic compounds.

24 Evolution as a Unifying Theme zDarwin’s Origin of Species (1850) yObservations while on the HMS Beagle yModel: Evolution xIndividuals vary in their fitness in the environment xStruggle for existence and survival of the most fit xOrigin of species via incremental changes in form and function (relate back to observation while on the Beagle) zLink to Mendel and the Particulate Model of Inheritance (1860’s) zLink to Watson and Crick (1956) and the discovery of DNA zExamples of evolution in action zSignificance of evolution as a theory in Biology

25 Structural Features of Living Systems zUbiquitous nature of “cells” and its hierarchy yPhysical, chemical and biological basis for a cell (adaptation) ySuggestion of a common progenitor/ancestor yPhysical dimensions of a cell (maximum size) zUbiquitous nature of “organelle” yEfficacy of metabolism (random) yDiversity of function yDiversity of structure ySimilarity of structure

26 Structural Features of Living Systems zEvolution of cell types yProkaryotes xCell, membranes but no nucleus xExamples: bacteria yEukaryotes xCell, membrane, and nucleus xAll higher plants and animals

27 Biochemical Features of Living Systems zCarbon-based economy yAbundance in the universe yAtomic structure (electrons, protons, etc.) yChemical properties (bonding) zMetabolism yCatabolism and biosynthesis yEnergy capture and utilization xATP and ADP

28 Biochemical Features of Living Systems zBiochemicals or biomacromolecules yDefine polymer zCarbohydrates (CH 2 O) zLipids (fatty acids + glycerol) zProteins (amino acids & polypeptides) zNucleic Acids (nucleotides) zPoints to a common ancestor

29 Biochemical Pathways

30 Molecular Features of Living Systems zGenes and genomes zReplication of DNA zTranscription, translation, and the genetic code zPolypeptides and proteins zBiological catalysis: enzymes zGene regulation and genetic engineering zPoints to a common ancestor

31 Molecular Features of Living Systems (continued) DNA m-RNA t-RNA Polypeptide Functional Protein Transcription Translation Translation/Genetic Code Conformation

32 Instructional Features of Living Systems: Genetic Code zSequence of base pairs (ATCG) on mRNA (DNA) used to “program” sequence of amino acids z20 different amino in living systems (60+ total in nature) zReading the ‘tea leaves” of the genetic code helps understand evolution of life

33 Instructional Features of Living Systems: Genetic Code (cont’d) zGenetic code and “triplets” y4 different nucleotides (base pairs) y20 different amino acids yHow does 1 nucleotide specify 1 amino acid? (N=4) zOptions y2 letter code sequence (e.g.,T-A) for 1 amino acid (N= 16) y3 letter code sequence (e.g., T-A-G) for 1 amino acid (N=64)…more than adequate since there are only 20 z“Triplet Code” yCCG calls for proline yAGT calls for serine

34 Amino Acid Codons

35 iClicker Question zThe codon CAA is translated by your genes as which amino acid? yALeucine yBProline yCGlutamine yDHistadine yEArginine

36 iClicker Question zThe codon CAG is translated by your genes as which amino acid? yALeucine yBProline yCGlutamine yDHistadine yEArginine

37 iClicker Question zThe codon GC_ is translated by your genes as alanine? yAU yBC yCA yDG yEAll of the above.

38 iClicker Question zThe codon AC_ is translated by your genes as threonine? yAU yBC yCA yDG yEAll of the above.

39 iClicker Question zWhich of the following codons are translated by your genes as the stop signal? yAUAA yBUAG yCUGA yDAll of the above.

40 iClicker Question zWhich of the following codons are translated by your genes as the start signal? yAUAA yBUAG yCUGA yDAUG yEAll of the above.

41 Mutations and Evolution zMutation at the molecular level yDefine yCauses xEnvironment (examples) xEndogenous (e.g., replication) zFitness of mutation yNegative fitness (extreme is lethal) yPositive fitness yNeutral fitness zRole in evolution

42 iClicker Question zWhich of the following is not considered a key piece of evidence supporting a common ancestor for all life on Earth? yAThe fact that all life on Earth is carbon- based. yBThe fact that all life on Earth uses the molecule ATP to store and release energy. yCThe fact that life on Earth builds proteins from the same set of left-handed amino acids.

43 iClicker Question zAn organism’s heredity is encoded in yADNA yBATP yCLipids

44 iClicker Question zAn enzyme consists of a chain of yAcarbohydrates. yBamino acids. yCnucleic acids.

45 iClicker Question zWhich of the following mutations would you expect to have the greatest effect on a living cell? yAA mutation that changes a single base in a region of noncoding DNA. yBA mutation that changes the third letter of one of the three-base “words” in a particular gene. yCA mutation that deletes one base in the middle of a gene.

46 EXTREMOPHILES NATURE’S ULTIMATE SURVIVORS Adapted from HOUSSEIN A. ZORKOT, ROBERT WILLIAMS, and ALI AHMAD UNIVERSITY OF MICHIGAN-DEARBORN

47 What are Extremophiles? zExtremophiles are microorganisms yviruses, prokaryotes, or eukaryotes zExtremophiles live under unusual environmental conditions yatypical temperature, pH, salinity, pressure, nutrient, oxic, water, and radiation levels

48 Types of Extremophiles

49 More Types of Extremophiles zBarophiles ysurvive under high pressure levels, especially in deep sea vents zOsmophiles ysurvive in high sugar environments zXerophiles ysurvive in hot deserts where water is scarce zAnaerobes ysurvive in habitats lacking oxygen zMicroaerophiles ythrive under low-oxygen conditions zEndoliths ydwell in rocks and caves zToxitolerants yorganisms able to withstand high levels of damaging agents. For example, living in water saturated with benzene, or in the water-core of a nuclear reactor

50 Environmental Requirements

51

52 EXTREME PROKARYOTES Hyperthermophiles -Members of domains Bacteria and Archaea -Possibly the earliest organisms -Early earth was excessively hot, so these organisms would have been able to survive

53 Morphology of Hyperthermophiles Heat stable proteins that have more hydrophobic interiors prevents unfolding or denaturation at higher temperatures Chaperonin proteins maintain folding Monolayer membranes of dibiphytanyl tetraethers saturated fatty acids which confer rigidity, prevent degradation in high temperatures A variety of DNA-preserving substances that reduce mutations and damage to nucleic acids e.g., reverse DNA gyrase and Sac7d Can live without sunlight or organic carbon as food survive on sulfur, hydrogen, and other materials that other organisms cannot metabolize The red on these rocks is produced by Sulfolobus solfataricus, near Naples, Italy

54 Sample Hyperthermophiles Thermus aquaticus 1  m Pyrococcus abyssi 1  m Frequent habitats include volcanic vents and hot springs, as in the image to the left

55 Deep Sea Extremophiles zDeep-sea floor and hydrothermal vents involve the following conditions: ylow temperatures (2-3º C) – where only psychrophiles are present ylow nutrient levels – where only oligotrophs present yhigh pressures – which increase at the rate of 1 atm for every 10 meters in depth (as we have learned, increased pressure leads to decreased enzyme- substrate binding) zbarotolerant microorganisms live at meters zbarophilic microorganisms live at depths greater than 4000 meters A black smoker, i.e. a submarine hot spring, which can reach °F ( °C)

56 Extremophiles of Hydrothermal Vents A cross-section of a bacterium isolated from a vent. Often such bacteria are filled with viral particles which are abundant in hydrothermal vents A bacterial community from a deep-sea hydrothermal vent near the Azores Natural springs vent warm or hot water on the sea floor near mid-ocean ridges Associated with the spreading of the Earth’s crust. High temperatures and pressures 0.2  m 1m1m

57 Psychrophiles Some microorganisms thrive in temperatures below the freezing point of water (this location in Antarctica) Some people believe that psychrophiles live in conditions mirroring those found on Mars – but is this true?

58 zProteins rich in  -helices and polar groups y allow for greater flexibility z“Antifreeze proteins” y maintain liquid intracellular conditions by lowering freezing points of other biomolecules zMembranes that are more fluid y contain unsaturated cis-fatty acids which help to prevent freezing zactive transport at lower temperatures Characteristics of Psychrophiles

59 Halophiles Divided into classes mild (1-6%NaCl) moderate (6-15%NaCl) extreme (15-30%NaCl) Mostly obligate aerobic archaea Survive high salt concentrations by interacting more strongly with water such as using more negatively charged amino acids in key structures making many small proteins inside the cell, and these, then, compete for the water accumulating high levels of salt in the cell in order to outweigh the salt outside

60 Barophiles Survive under levels of pressure that are lethal to most organisms Found deep in the Earth, in deep sea, hydrothermal vents, etc. A sample of barophilic bacteria from the earth’s interior 1m1m

61 Xerophiles Extremophiles which live in water-scarce habitats, such as deserts Produce desert varnish as seen in the image to the left a thin coating of Mn, Fe, and clay on the surface of desert rocks, formed by colonies of bacteria living on the rock surface for thousands of years

62 SAMPLE PROKARYOTE EXTREMOPHILES ThermotogaAquifex Halobacterium MethanosarcinaThermoplasma Thermococcus ThermoproteusPyrodictiumIgnicoccus 2um 1.8um 1um 0.6um0.9um 1.3um 0.6um 0.7um

63 Deinococcus radiodurans -Possess extreme resistance to up to 4 million rad of radiation, genotoxic chemicals (those that harm DNA), oxidative damage from peroxides/superoxides, high levels of ionizing and ultraviolet radiation, and dehydration -It has from four to ten DNA molecules compared to only one for most other bacteria -Contain many DNA repair enzymes, such as RecA, which matches the shattered pieces of DNA and splices them back together. During these repairs, cell-building activities are shut off and the broken DNA pieces are kept in place 0.8  m

64 Chroococcidiopsis A cyanobacteria which can survive in a variety of harsh environments hot springs, hypersaline habitats, hot, arid deserts, and Antarctica Possesses a variety of enzymes which assist in such adaptation 1.5  m

65 iClicker Question zA thermophile is a type of extremophile that can survive ambient conditions with yArelatively high pressures yBrelatively high temperatures yCrelatively low temperatures yDrelatively salty extremes yErelatively low pressures

66 iClicker Question zA psychrophile is a type of extremophile that can survive ambient conditions with yArelatively high pressures yBrelatively high temperatures yCrelatively low temperatures yDrelatively salty extremes yErelatively low pressures

67 iClicker Question zA barophile is a type of extremophile that can survive ambient conditions with yArelatively high pressures yBrelatively high temperatures yCrelatively low temperatures yDrelatively salty extremes yErelatively low pressures

68 iClicker Question zA halophile is a type of extremophile that can survive ambient conditions with yArelatively high pressures yBrelatively high temperatures yCrelatively low temperatures yDrelatively salty extremes yErelatively low pressures

69 Other Prokaryotic Extremophiles Gallionella ferrugineaand (iron bacteria), from a cave Anaerobic bacteria 1m1m1m1m Current efforts in microbial taxonomy are isolating more and more previously undiscovered extremophile species, in places where life was least expected

70 EXTREME EUKARYOTES THERMOPHILES/ACIDOPHILES 2m2m

71 EXTREME EUKARYOTES PSYCHROPHILES Snow Algae (Chlamydomonas nivalis) A bloom of Chloromonas rubroleosa in Antarctica These algae have successfully adapted to their harsh environment through the development of a number of adaptive features which include pigments to protect against high light, polyols (sugar alcohols, e.g. glycerine), sugars and lipids (oils), mucilage sheaths, motile stages and spore formation 2m2m

72 EXTREME EUKARYOTES ENDOLITHS Quartzite (Johnson Canyon, California) with green bands of endolithic algae. The sample is 9.5 cm wide. -Endoliths (also called hypoliths) are usually algae, but can also be prokaryotic cyanobacteria, that exist within rocks and caves -Often are exposed to anoxic (no oxygen) and anhydric (no water) environments

73 EXTREME EUKARYOTES Parasites as extremophiles -Members of the Phylum Protozoa, which are regarded as the earliest eukaryotes to evolve, are mostly parasites -Parasitism is often a stressful relationship on both host and parasite, so they are considered extremophiles Trypanosoma gambiense, causes African sleeping sickness Balantidium coli, causes dysentery-like symptoms 15  m 20  m

74 EXTREME VIRUSES Virus-like particles isolated from Yellowstone National Park hot springs Viruses are currently being isolated from habitats where temperatures exceed 200°F Instead of the usual icosahedral or rod-shaped capsids that known viruses possess, researchers have found viruses with novel propeller-like structures These extreme viruses often live in hyperthermophile prokaryotes such as Sulfolobus 40nm

75 Phylogenetic Relationships Extremophiles are present among Bacteria, form the majority of Archaea, and also a few among the Eukarya

76 zMembers of Domain Bacteria (such as Aquifex and Thermotoga) that are closer to the root of the “tree of life” tend to be hyperthermophilic extremophiles zThe Domain Archaea contain a multitude of extremophilic species: yPhylum Euryarchaeota-consists of methanogens and extreme halophiles yPhylum Crenarchaeota-consists of thermoacidophiles, which are extremophiles that live in hot, sulfur-rich, and acidic solfatara springs yPhylum Korarchaeota-new phylum of yet uncultured archaea near the root of the Archaea branch, all are hyperthermophiles zMost extremophilic members of the Domain Eukarya are red and green algae PHYLOGENETIC RELATIONSHIPS

77 Chronology of Life

78 What were the first organisms? zEarly Earth largely inhospitable yhigh CO 2 /H 2 S/H 2 etc, low oxygen, and high temperatures zLifeforms that could evolve in such an environment needed to adapt to these extreme conditions zH 2 was present in abundance in the early atmosphere yMany hyperthermophiles and archaea are H 2 oxidizers zExtremophiles may represent the earliest forms of life with non-extreme forms evolving after cyanobacteria had accumulated enough O 2 in the atmosphere zResults of rRNA and other molecular techniques have placed hyperthermophilic bacteria and archaea at the roots of the phylogenetic tree of life

79 Evolutionary Theories zConsortia ysymbiotic relationships between microorganisms, allows more than one species to exist in extreme habitats because one species provides nutrients to the others and vice versa zGenetic drift appears to have played a major role in how extremophiles evolved, with allele frequencies randomly changing in a microbial population. ySo alleles that conferred adaptation to harsh habitats increased in the population, giving rise to extremophile populations zGeographic isolation may also be a significant factor in extremophile evolution. yMicroorganisms that became isolated in more extreme areas may have evolved biochemical and morphological characteristics which enhanced survival as opposed to their relatives in more temperate areas. This involves genetic drift as well

80 Pace of Evolution zExtremophiles, especially hyperthermophiles, possess slow “evolutionary clocks” y They have not evolved much from their ancestors as compared to other organisms y Hyperthermophiles today are similar to hyperthermophiles of over 3 billion years ago zSlower evolution may be the direct result of living in extreme habitats and little competition zOther extremophiles, such as extreme halophiles and psychrophiles, appear to have undergone faster modes of evolution since they live in more specialized habitats that are not representative of early earth conditions

81 Mat Consortia Microbial mats consist of an upper layer of photosynthetic bacteria, with a lower layer of nonphotosynthetic bacteria These consortia may explain some of the evolution that has taken place: extremophiles may have relied on other extremophiles and non- extremophiles for nutrients and shelter Hence, evolution could have been cooperative A mat consortia in Yellowstone National Park

82 Use of Hyperthermophiles HYPERTHERMOPHILES (SOURCE)USE DNA polymerases DNA amplification by PCR Alkaline phosphatase Diagnostics Proteases and lipases Dairy products Lipases, pullulanases and proteasesDetergents Proteases Baking and brewing and amino acid production from keratin Amylases, a-glucosidase, pullulanase and xylose/glucose isomerases Baking and brewing and amino acid production from keratin Alcohol dehydrogenase Chemical synthesis Xylanases Paper bleaching Lenthionin Pharmaceutical S-layer proteins and lipids Molecular sieves Oil degrading microorganisms Surfactants for oil recovery Sulfur oxidizing microorganisms Bioleaching, coal & waste gas desulfurization Hyperthermophilic consortia Waste treatment and methane production

83 Use of Psychrophiles PSYCHROPHILES (SOURCE)USE Alkaline phosphataseMolecular biology Proteases, lipases, cellulases and amylases Detergents Lipases and proteasesCheese manufacture and dairy production ProteasesContact-lens cleaning solutions, meat tenderizing Polyunsaturated fatty acidsFood additives, dietary supplements Various enzymesModifying flavors b-galactosidaseLactose hydrolysis in milk products Ice nucleating proteinsArtificial snow, ice cream, other freezing applications in the food industry Ice minus microorganismsFrost protectants for sensitive plants Various enzymes (e.g. dehydrogenases) Biotransformations Various enzymes (e.g. oxidases)Bioremediation, environmental biosensors MethanogensMethane production

84 Use of Halophiles HALOPHILES (SOURCE)USE BacteriorhodopsinOptical switches and photocurrent generators in bioelectronics PolyhydroxyalkanoatesMedical plastics Rheological polymersOil recovery Eukaryotic homologues (e.g. myc oncogene product) Cancer detection, screening anti-tumor drugs LipidsLiposomes for drug delivery and cosmetic packaging LipidsHeating oil Compatible solutesProtein and cell protectants in variety of industrial uses, e.g. freezing, heating Various enzymes, e.g. nucleases, amylases, proteases Various industrial uses, e.g. flavoring agents g-linoleic acid, b-carotene and cell extracts, e.g. Spirulina and Dunaliella Health foods, dietary supplements, food coloring and feedstock MicroorganismsFermenting fish sauces and modifying food textures and flavors MicroorganismsWaste transformation and degradation, e.g. hypersaline waste brines contaminated with a wide range of organics MembranesSurfactants for pharmaceuticals

85 Use of Alkaliphiles and Acidophiles ALKALIPHILES (SOURCE)USES Proteases, cellulases, xylanases, lipases and pullulanasesDetergents ProteasesGelatin removal on X-ray film Elastases, keritinasesHide dehairing CyclodextrinsFoodstuffs, chemicals and pharmaceuticals Xylanases and proteasesPulp bleaching PectinasesFine papers, waste treatment and degumming Alkaliphilic halophilesOil recovery Various microorganismsAntibiotics ACIDOPHILES (SOURCE)USES Sulfur oxidizing microorganismsRecovery of metals and desulfurication of coal MicroorganismsOrganic acids and solvents

86 Taq Polymerase Isolated from the hyperthermophile Thermus aquaticus Much more heat stable Used as the DNA polymerase in Polymerase Chain Reaction (PCR) technique which amplifies DNA samples

87 Alcohol Dehydrogenase zAlcohol dehydrogenase (ADH), is derived from a member of the archaea called Sulfolobus solfataricus  It can survive to 88°C (190 º F) - nearly boiling - and corrosive acid conditions (pH=3.5) approaching the sulfuric acid found in a car battery (pH=2) zADH catalyzes the conversion of alcohols and has considerable potential for biotechnology applications due to its stability under these extreme conditions

88 Bacteriorhodopsin -Bacteriorhodopsin is a trans-membrane protein found in the cellular membrane of Halobacterium salinarium, which functions as a light- driven proton pump -Can be used for generation of electricity

89 Bioremediation -Bioremediation is the branch of biotechnology that uses biological processes to overcome environmental problems -Bioremediation is often used to degrade xenobiotics introduced into the environment through human error or negligence - Part of the cleanup effort after the 1989 Exxon Valdez oil spill included microorganisms induced to grow via nitrogen enrichment of the contaminated soil

90 Bioremediation

91 -Bioremediation applications with cold-adapted enzymes are being considered for the degradation of diesel oil and polychlorinated biphenyls (PCBs) -Health effects associated with exposure to PCBs include -acne-like skin conditions in adults -neurobehavioral and immunological changes in children -cancer in animals Psychrophiles as Bioremediators

92 Life in Outer Space? zMajor requirements for life: ywater yenergy ycarbon zAstrobiologists are looking for signs of life on Mars, Jupiter’s moon Europa, and Saturn’s moon Titan zIf such life exists it must consist of extremophiles y withstand the cold and pressure differences of these worlds

93 Life in Outer Space? Europa is may have an ice crust shielding a 30-mile deep ocean. Reddish cracks (left) are visible in the ice – what are they? Titan is enveloped with hazy nitrogen (left) Contains organic molecules May provide sustenance for life?

94 Life in Outer Space? Some meteorites contain amino acids and simple sugars Maybe serve to spread life throughout the universe? Image courtesy of the Current Science & Technology Center A sample of stratospheric air myriad of bacterial diversity 41 km above the earth’s surface (Lloyd, Harris, & Narlikar, 2001)

95 CONCLUSIONS zHow are extremophiles important to astrobiology? yreveal much about the earth’s history and origins of life ypossess amazing capabilities to survive in extreme environments yare beneficial to both humans and the environment ymay exist beyond earth

96 iClicker Question zPeople belong to domain yAEukarya yBArchaea yCBacteria

97 iClicker Question zGenerally speaking, an extremophile is an organism that yAthrives in conditions that would be lethal to humans and other animals. yBcould potentially survive in space. yCis extremely small compared to most other life on Earth.

98 iClicker Question zBased upon what you have learned in this chapter, it seems reasonable to think that life could survive in each of the following habitats except for yArock beneath Mars’ surface. yBa liquid ocean beneath the icy crust of Jupiter’s moon Europa. yCwithin ice that is perpetually frozen in a crater near the Moon’s south pole.

99 Cartoons to Help You Remember